To get that look, you'll not only have to remove the lacquer, but also either sand or media-blast the brass. Sanding gives more of a dull "scratch" finish, while blasting gives it more of a "frosted" look. With no lacquer to protect the new treatment, though, it will tarnish and not look cool for long. If you want to maintain the sheen, polishing will eventually remove the treatment. Don't expect any change in how the horn plays, though.